Method

To begin with, measure the crème fraîche into a medium saucepan and bring to a gentle simmer.

Add some freshly milled black pepper but don't add salt yet because the haddock can be quite salty. Then pop in the prepared fish and let it poach gently, uncovered, for about 5 minutes. Meanwhile, make up the sauce: separate one of the eggs, breaking the yolk into a small bowl and reserving the white in another bowl. Add the cornflour to the yolk and whisk well. When the fish is cooked, use a draining spoon to lift it out into a sieve placed over the saucepan, to allow the liquid to drain back. Press lightly to extract every last drop of liquid, then place the sieve containing the fish on a plate.

At this point pre-heat the grill to its highest setting. Now bring the liquid in the pan back up to simmering point, then pour it on to the egg yolk, whisking all the time. Then return the whole mixture to the saucepan and gently bring it back to just below simmering point or until it has thickened – no more than one or two minutes. After that, remove it from the heat and stir in the cooked haddock, tasting to see if it needs any salt. Next, whisk up the egg white to the soft-peak stage and carefully fold it into the haddock mixture.

Now for the omelette. First beat the 4 remaining eggs with some seasoning. Next, melt the butter and oil in a frying pan until foaming, swirling them round to coat the sides and base. When it's very hot add the eggs, let them settle for about 2 minutes, then begin to draw the edges into the centre, tilting the pan to let the liquid egg run into the gaps. When you feel the eggs are half set, turn the heat down and spoon the haddock mixture evenly over the surface of the eggs, using a palette knife to spread it. Now sprinkle the Gruyère over the top and place the omelette pan under the grill, positioning it roughly 5 inches (13 cm) from the heat source. The omelette will now take 2-3 minutes to become puffy, golden brown and bubbling. Remove it from the grill, let it settle and relax for 5 minutes before cutting into wedges and serving on warmed plates.